A High Performance and Portable Optically Pumped Cesium Beam Frequency Standard

As optical frequency standard [1]–[4] and frequency comb developed with quite high precision(10−18 or 10−19) and commercial H-maser developed with quite good short-term stability(10−15), the only and core competitiveness of Cesium beam frequency standards(CBFS) are reliability and long-term stability today. We developed a high performance and portable optically pumped CBFS and the instability is $3\times 10^{-13}/\sqrt{\tau}$ with the flicker floor expecting to be $3\times 10^{-15}$ . It has the best longterm performance of the optically pumped CBFS operated with an 852nm distributed feedback(DFB) laser ever measured with such a good short-term stability. Such a good result is attributed to the excellent control of the microwave power, C field and laser power. The portable CBFS can be used in many fields and is getting ripeness to substitute the existing magnetic selected products.